Domain names are linked to IP addresses. For ease of use, characters of the Latin alphabet are typically used. Some web developers tend to pass descriptive attributes in the URL to represent data hierarchies, command structures, transaction paths and session information. As a result, very long URLs may be created making it difficult for users to type or remember. Uniform Resource Locator (URL) shortening is a technique on the World Wide Web in which a URL may be made substantially shorter in length. The technique involves using a Hypertext Transfer Protocol (HTTP) redirect on a domain name that is short to link to a website which has a long URL. URL shortening sites have become increasingly popular enabling URLs of any length to be shortened to easy-to-remember/type versions.
A short URL obscures the target address, and as a result it may be used to redirect to an unexpected site. Thus, malicious behaviors like rick-rolling, redirecting to scam and affiliate websites, or shock sites may take advantage of this web tool. URL shortening websites may inadvertently distribute spyware. Opaqueness is also used by spammers, who use such links in spam to bypass URL blacklists. It is typically impossible for a user to know from the short URL whether or not it points to a suspicious site, so users can be conned into clicking malicious links.